diff --git a/report_builder/mixins.py b/report_builder/mixins.py
index 711ad092..2dcdb87a 100644
--- a/report_builder/mixins.py
+++ b/report_builder/mixins.py
@@ -109,6 +109,7 @@ def build_csv_response(self, wb, title="report"):
     def list_to_workbook(self, data, title='report', header=None, widths=None):
         """ Create just a openpxl workbook from a list of data """
         wb = Workbook()
+        wb.guess_types = True
         title = re.sub(r'\W+', '', title)[:30]
 
         if isinstance(data, dict):